Small secret committees decide whether or not your health insurance will cover the drugs you need. Surprise ! Expensive newer drugs often don't get covered, even though, as mentioned in the article below, they can offer significant benefits for people with things like terrible migraines. (The example used: 3 new migraine drugs that greatly reduce the incidence of migraines -- but are expensive, so no coverage.)

https://www.reuters.com/article/us-usa-drugpr...SKCN1S51E7